Rabies, EIA Confirmed in Colorado Horses

The Colorado Department of Agriculture (CDA) announced April 29 that a horse in Logan County was recently confirmed positive for rabies, while a horse in Garfield County tested positive for equine infectious anemia (EIA).

In regards to the rabies case, the CDA is encouraging livestock and pet owners to discuss animal health concerns, including the need for rabies vaccination, with their local veterinarian after the horse residing in northeast Colorado was euthanized and subsequently tested positive for rabies.

“The department would like to stress two very important points,” said State Veterinarian Keith Roehr, DVM. “One, owners should monitor their animals for clinical signs of rabies, and two, local veterinarians are a valuable resource to help producers decide the best course of action to protect their livestock and pets from rabies.” Livestock and pet owners are encouraged to discuss vaccination with their veterinarian for animals that could be exposed to wildlife that carry and could transmit the rabies virus to dogs, cats, horses, small ruminants, llamas, alpacas, and petting zoo animals.

Rabies is a viral disease infecting the brain and central nervous system. The clinical appearance of rabies typically falls into two types: “aggressive” and “dumb.” Aggressive rabies symptoms include combativeness and violent behavior and sensitivity to touch and other kinds of stimulation. There is also a “dumb” form of the disease in which the animal is lethargic, weak in one or more limbs, and unable to raise its head or make sounds because its throat and neck muscles are paralyzed.

Rabies can be passed from animals to humans. Rabies is spread primarily through the bite of rabid animals, resulting in the spread of the disease through their infected saliva. Rabies also can be spread when saliva from an infected animal gets into open wounds or cuts, or enters through membranes of the eyes, nose, or mouth. No cure exists for rabies once clinical signs appear although there is a vaccine to prevent the infection.

“Animal owners need to primarily look for any dramatic behavioral changes,” said Roehr. “That is typically one of the hallmark signs that the animal may be suffering from rabies.”

Meanwhile, in regards to the EIA case confirmed in Garfield County, the CDA said that the herdmates of the affected horse have tested negative to EIA and neighboring horses will be tested to rule out any spread by insect vector.

“Identifying infected horses and restricting their contact with susceptible animals is the key to preventing the spread of this disease,” said Roehr. “EIA is transmitted through biting flies, the most common would be deer and horse flies. Horse owners can protect their herd by control biting flies around the stable and other areas where horses are kept.”

EIA is an equid disease that can cause fever, anemia, fluid accumulation on the chest or legs, and emaciation in some animals. The virus can also cross the placental barrier to cause fetal infection. Many horses do not show any clinical signs of disease or have very mild signs on first exposure, and carry the virus subclinically. All infected horses, including those that are asymptomatic, are potential carriers and are considered infectious for life. Infected animals must either be destroyed or remain permanently isolated from other equids to prevent transmission. There is currently no vaccine to protect a horse against EIA.

A blood test to detect the disease is called a Coggins test and it is required for equids entering Colorado and is recommended for all horses that change ownership or attend equine events.

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